Understanding a Learning Goal or Standard


Fill in each part, Dan - fogleman fogleman Oct 14, 2007

Life Science, Content Standard C
Molecular basis of heredity

  • Most of the cells in a human contain two copies of each 22 different chromosomes. In addition, there is a pair of chromosomes that determines sex: a female contains two X chromosomes and a male contains one X and one Y chromosome. Transmission of genetic information to offspring occurs through egg and sperm cells that contain only one representative from each chromosome pair. An egg and a sperm unite to form a new individual. The fact that the human body is formed from cells that contain two copies of each chromosome and therefore two copies of each gene explains many factures of human heredity, such as how variations that are hidden in one generation can be expressed in the next.



What does the standard mean?
  • Every human has 22 pairs chromosomes, half from mother and half from father do to sexual reproduction.
  • Chromosomes have DNA information which do to meiosis will bring out different traits and expression.
  • Mendel experiments with the pea plant brought about a great amount of knowledge of traits and gene expression. It explains the foundation of the P, F1 and F2 generations.
  • With gene expression, there are dominant and recessive alleles that make indivuals have diffrent genotype and phenotypes.
  • This can all be shown through Punnett squares.
  • In heredity we can use pedigree charts to show how genetic disorders skip generations as well as sex linked traits.
  • There is also blood typing through punnett squares which can show it diffrent blood types can be passed through generations.
  • Multiple alleles that show how some traits are determined by more then two allels.



What do students need to understand before you can address this topic?
  • Mitosis
  • DNA/ RNA
  • What is a gene



What prior (mis)understandings are students likely to have about these topics?
  • Where genes come from.
  • Ex. Your hair comes from your mothers’ father.
  • If my parents don’t have a disorder then I can’t have it.



Planning Resources: Representations/Phenomena/Activity Ideas

Include links to online resources and descriptions of print resources you think will be useful.


Link to Resource
Description of Resource, Representation, or Phenomena: